Recent multi-messenger observations with radio waves, \(X\) -rays, and gravitational waves associated with neutron star phenomena have provided with important information on various phases and properties of highly dense matter: The observations of massive neutron stars as large as 2 \(M_\odot \)  (\(M_\odot \)  being the solar mass) have put stringent constraint on the EOS [1]}, [2]}, [3]}, [4]}.
The detection of gravitational waves from neutron-star mergers (GW170817) [5]}, [6]} and
measurements of mass and radius of neutron stars through \(X\) -ray observation by Neutron star Interior Composition ExploreR (NICER) [7]}, [8]} have shed light on constraining the EOS of dense matter.
